Protective dial assembly for permutation locks



Oct. 5, 1954 H. c. MILLER 2,690,664

PROTECTIVE DIAL ASSEMBLY FOR PERMUTATION LOCKS Filed July 15, 1953 ATTORNEYS Patented Oct. 5, 1954 UlTED STATES ATENT OFFICE PROTECTIVE DIAL ASSEMBLY FOR PERMUTATI-ON LOCKS 6 Claims.

The present invention relates in general to permutation locks, and more particularly to a dial and dial ring assembly for permutation locks affording security against detection by a distant observer of the combination used in opening the lock.

It has been long recognized that the combinations of permutation locks are subject to theft by unauthorized viewing of the successive registrations of the dial markings occurring during opening of the lock. Where such a lock is opened in the presence of other persons, it is a simple matter for such persons to note the combination from a point removed from the operators position and thereafter gain unauthorized access to the closure secured by the lock.

Heretofore, various means have been provided to be used in connection with conventional combination lock dials, which shield the greater portion of the dial from view by unauthorized persons. These have generally taken the form of a shield or cover provided with a window exposing only a limited number of the dial markings to view along an axis perpendicular to the face of the dial. Such dial shields have the dual purpose of hampering observation of the dial num" bers by persons to either side of the operator while the operator is dialing the combination, and limiting the range of exposed dial markings which are visible so that the body of the operator will shield the exposed dial area from observation by persons at remote locations to the rear of the operator. These dial shields, however, are usually in the form of additional accessories which must be associated with the combination lock and dial, and in many cases afford such a limited visible dial area that the lock dial must be operated very slowly in order to bring the proper numbers on the dial into registry with the index mark. Also because of the restricted visible dial area, the numbers are often so obscured or difficult to count that the operator must make a number of attempts before the successful combination is dialed.

Another disadvantage of circular dial type combination locks, whether they are provided with dial shields or not, is that the dial and dial ring are uniformly formed of opaque material, so that the area of the safe or file cabinet wall immediately behind the dial and dial ring is not visible. It is a not uncommon practice for persons who are seeking unauthorized admission to the safe or file cabinet to open the lock by drilling a hole through the dial, the dial ring and the safe or file cabinet wall, into the lock housing,

2 at a point such that an instrument can be inserted into the lock housing to retract the bolt. In such instances, if the person then replaces the drilled opaque dial with an identical dial, it is not apparent thereafter that the lock has been tampered with.

An object of the present invention, therefore, is the provision of a novel dial and dial ring assembly for combination locks, which eifectively prevents unauthorized viewing of the dial markings as they are moved into registration with the index mark, without materially impairing or interfering with the operators vision of the markings.

Another object of the present invention is the provision of a novel dial assembly for combination locks constructed in such a manner that the surface area on which the dial assembly is supported is visible through the dial, thereby discouraging unauthorized actuation of the look by drilling through the dial supporting body.

Another object of the present invention is the novel construction of a dial assembly for combination locks, in which visibility of the dial markings to persons other than the operator is severely restricted and any apertures drilled through the dial supporting body to gain unauthorized admission to the lock are exposed to view.

Other objects, advantages and capabilities of the present invention will become apparent from the following detail description, taken in conjunction with the accompanying drawings, wherein only a preferred embodiment of the invention is illustrated.

In the drawing:

Figure 1 is a front elevation of a dial assembly for combination locks embodying the present invention, illustrated on a fragmentary portion of a safe door;

Figure 2 is a vertical transverse section View taken along the lines 2-2 of Figure 1; and

Figure 3 is a fragmentary vertical section view taken along the lines 3-3 of Figure 2, and illustrating the background sector for rendering a portion of the dial markings visible.

Referring to the drawings, wherein like reference characters designate corresponding parts through the several figures, the combination lock dial assembly, indicated generally by the reference character it, is adapted to be mounted on a closure panel I i, such as a safe door, a file cabinet drawer wall, or the like, in the conventional manner, and to be secured to the lock actuating spindle I2 projecting forwardly of the 3 closure panel H through a suitable aperture l3 therein from a combination lock housing 14 mounted on the inner surface of the closure panel H. The combination lock housing It and the lock components may be of any conventional form, such as that disclosed in my earlier U. S. Patent No. 2,575,674, issued November 20, 1951.

To this end, the dial assembly i is provided with a dial knob I5, preferably of truncated conical form, having a cylindrical bore Ni axially aligned with the knob and extending inwardly from the innermost face of the knob. The bore IS in accordance with conventional practice is designed to accommodate the lock spindle l2 and be fitted thereto so that rotation of the knob I5 is applied to the spindle l2. The knob l5 carries a disc shaped dial H, which is pro vided with a circular center aperture i8 accommodating the bottom of an annular rabbet 19 formed on the knob [5. In accordance with conventional practice, the dial i! is seated in the annular rabbet 19 formed on the knob 45 and is secured to the walls thereof.

The circular dial ii is formed of a transparent plastic material, such as Lucite or the like, which can be readily milled or molded to the desired shape. The rear surface 20 of the transparent plastic dial H is a plane surface and is provided adjacent the periphery of the dial with etched or otherwise indented radial lines and numbers 2| constituting the dial markings. As these etched dial markings would be invisible in this form, the etched areas are then filled in with stick paint or light opaque material of a color matching the color on the front surface of the closure panel H on which the dial assembly is supported.

Rearwardly of the dial [1, a dial ring 22 is provided. In accordance with conventional practice, the dial ring 22 is in the form of a circular body of greater radius than the dial ll, and is provided with a cylindrical recess 23 for accommodating the dial l! and an annular outwardly projecting convex portion 24 surrounding the outer periphery of the dial IT and provided at one point with a suitable opaque index mark 25. This dial ring 22 is preferably provided with a pair of diametrically opposed countersunk apertures 26 adapted to receive mounting screws 21 for mounting the dial ring 22 on the closure panel Ii, and is further provided with a central aperture 28 for accommodating the innermost portion of the knob i5 and forming a bearing therefor.

To render visible the dial markings formed of the etched areas 2| filled in with stick paint matching that on the closure panel surface, a background body 30 in the shape of a pie-shaped sector of a radius equal to or greater than the radius of the dial ll, is mounted on the front face of the closure panel II and positioned to be bisected by the radial axis extending from the spindle l2 through the index mark 25. This background body 36 is preferably of a light color, and extends over an arc corresponding to approximately twenty points along the dial markings, so as to render the dial markings overlying the background plate 30 visible to the operator of the lock.

It will be apparent from the above description that only those portions of the dial markings 2! which are directly in front of the background plate 36 are visible, as all of the dial marking indentations are filled with a paint matching in color the paint on the supporting surface and only the color of the background plate 30 will afford sufficient color contrast to render these markings visible. When the lock operator stands in front of the dial and operates the lock, his body sufficiently obscures the visible area of the dial from view by those stationed to the side or behind the operator so that such observers Will not be able to detect the combination being dialed.

The particular construction of the dial assembly therefore will effectively prevent any person from observing through a telescope or binoculars from a remote station to the rear of the operator, the combination being dialed, and would severely restrict any person beside and back of the operator from observing the combination being dialed.

Further because of the transparent character of the dial 6'! and dial ring 22, any drill hole or other evidences of tampering which modify the surface of the closure panel or other supporting body of the dial assembly are immediately visible through the dial assembly, whether the original dial is undeformed by the tampering or a new dial is substituted. In the latter case, the substituted dial must of course be of the same transparent character as the original dial.

While but one particular embodiment of the invention has been particularly shown and described, it is apparent that various modifications may be made in the invention without departing from the spirit and scope thereof, and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and are set forth in the appended claims.

What is claimed is:

1. In a dial assembly for permutation looks, a circular dial of translucent material adapted to actuate the lock, said dial having indicia-denoting indentations adjacent the periphery thereof in the rearwar ly disposed surface of said dial, matter of a color matching the coloring of a surface against which the dial is to be mounted occupying said indentations, and means underlying a limited arcuate segment of said dial adjacent the periphery thereof presenting a contrasting background to the colored matter occupying said indentations to render the in dentations overlying the same visible.

2. In a dial assembly for permutation locks, a circular dial formed of transparent material, said dial having indicia-denoting indentations adjacent the periphery thereof in the rearwardly disposed surface of said dial, paint of a color matching the coloring of a surface against which the dial is to be mounted occupying said indentations, and a background body underlying a limited arcuate segment of said dial adjacent the periphery thereof presenting a contrasting background to the paint occupying said indentations to render said indentations visible.

3. The combination with a permutation lock mounted on a closure panel, of a dial assembly comprising a circular dial of transparent material, said dial having indicia-denoting and radial peripheral indentations in the rearwardly disposed surface thereof, paint disposed in each of said indentations of a color matching the coloring of the outer surface of the closure panel supporting the permutation lock, and a sector of sheet material underlying an arcuate segment of said dial adjacent the periphery thereof corresponding substantially to twenty of said radial dial indentations said sector having a front surface of a color presenting a contrasting background to the paint occupying said indentations to render the indentations overlying said sector visible.

4. A dial assembly for permutation locks comprising a circular dial of translucent material, said dial having indiciadenoting indentations adjacent the periphery thereof in the rearwardly disposed surface of said dial, paint of a color matching the coloring of a surface adjacent which the dial is to be mounted occupying said indentations, a circular dial ring of translucent material adapted to be supported in fixed position and coaxially mounted relative to said dial in underlying relation therewith, and means positioned in fixed relation to said dial ring underlying a limited arcuate segment of said dial adjacent the periphery thereof and presenting a contrasting background to the paint occupying said indentations to render the indentations overlying the same visible.

5. The combination with a permutation lock mounted on a closure panel, of a dial assembly comprising a circular dial of transparent material, said dial having indicia-denoting and radial peripheral indentations in the rearwardly disposed surface thereof, paint disposed in each of said indentations of a color matching the coloring of the outer surface of the closure panel supporting the permutation look, a dial ring of transparent material coaxially mounted relative to said dial in underlying relation thereto, and a sector of sheet material underlying an arcuate segment of said dial adjacent the periphery thereof corresponding substantially to twenty of said radial dial indentations positioned in fixed relation relative to said dial ring, said sector having a front .surface of a color presenting a contrasting background to the paint occupying said indentations to render the indentations overlying said sector visible.

6. The combination with a permutation lock mounted on a closure panel, of a dial assembly comprising a circular dial of transparent material, said dial having indicia-denoting and raial peripheral indentations in the rearwardly disposed surface thereof, paint disposed in each of said indentations of a color matching the coloring of the outer surface of the closure panel supporting the permutation lock, a circular dial ring of transparent material of greater radius than said dial coaxially mounted relative to said dial and underlying the same in intimate contact with the outer surface of the closure panel, and a sector of sheet material underlying an arcuate segment of said dial adjacent the periphery thereof corresponding substantially to twenty of said radial dial indentations positioned in fixed relation relative to said dial ring, said sector having a front surface of a color presenting a contrasting background to the paint occupying said indentations to render the indentations overlying said sector visible.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date D. 171,117 Ball Dec. 22, 1953 1,166,231 Lewis Dec. 28, 1915 1,435,992 Strauss et a1. Nov. 21, 1922 1,652,897 Hill Dec. 13, 1927 1,926,809 Jacobson Sept. 12, 1933 2,427,896 Bradley Sept. 23, 1947 

